It is prior art knowledge that in connection with the manufacture of mineral wool, diabase, quartz, etc., has been melted, superheated and held at the desired temperature, in a tilting channel-type electric induction furnace, the furnace forming a sump in which a steel melt is held and heated by the inductor, the material to be heated floating on the melt and being thereby heated. The materials mentioned are of such low electrical conductivity as to be considered electrical non-conductors and, therefore, being incapable of being heated by electric currents.
The above technique would seem to have attractive possibilities in other fields. Oxides and sulfides of metals, either in the form of ores or products of manufacture, require to be fused and processed to obtain their metallic component, refinement or for other purposes. Minerals in general often require fusion and treatment. However, the previously referred to mineral wool manufacturing practice is known to involve undesirably low heat efficiency. For example, the diabase, quartz, etc., is first fused externally of the furnace, requiring a substantial expenditure of energy, the fused material then being poured into the furnace on top of the melt for heating and holding at the temperatures required for the mineral wool manufacturing. If chemical treatment is desired, such as is indicated in other fields, the reactive materials can only be dropped on top of the fused material floating on the steel melt.
The object of the present invention is to increase the heating efficiency of the described practice to an extent making its application more practical in other fields, and, in addition, to provide for making additions to either the melt or the material floating on the melt.